When Republicans cut taxes in the past, they did so only temporarily, bowing to Washington’s arcane budget rules that limited how much they could add to the federal deficit. They gambled — mostly successfully — that the tax cuts would not actually end because Democrats would eventually vote to continue them.

With this year’s tax cut, though, many Republicans no longer want to take that risk.

In the Senate, Republicans approved a budget outline on Saturday that opens the door to locking in the Trump tax cuts indefinitely without Democratic support.

Actually doing so would require Republicans to upend Senate procedures that have long governed what lawmakers can accomplish along party lines. That would mark a dramatic change in the hidebound institution, and invite Democrats to take major new steps of their own when they next control the chamber.

Senate Republicans believe that the Trump tax cuts are worth it. The party first passed the cuts in 2017, lowering individual income rates for most people, expanding the standard deduction and slashing corporate taxes.

Because they used standard Washington accounting methods at the time, many of the tax cuts are set to expire at the end of this year. Lawmakers are now facing a fiscal cliff that would increase taxes on many Americans if another bill isn’t passed.

Republicans acknowledge their good fortune in controlling Congress and the White House as the tax cuts come to an end. They can keep them going without having to negotiate with Democrats, who have sought to roll back some of the cuts.